Polyester resins reinforced with randomly oriented chopped glass fibers are commonly used to mold many products, such as automobile body components, bathtubs, machinery housings, and furniture. The use of chopped glass fiber substantially enhances the strength of the molded item. In a common production process, a hand-held gun is used to apply a mixture of polyester resin, glass fiber, and polymerizing catalyst in a mold, such as for a bathtub.
In one type of gun, the resin, and catalyst are mixed internally and then ejected from the front of the gun in a single stream. A chopper, powered by an air motor, chops strands of glass fiber into short pieces and then blows the chopped fibers into the resin/catalyst stream. A gun of this type has been marketed for several years by the assignee of the present application, Venus Products, Inc. of Kent, Wash. A drawback of this particular type of spray gun is that because the resin and catalyst are mixed internally within the gun, if the gun is not used, even for short periods of time, the resin will cure, thus plugging the gun. To prevent this from occurring, after each use of the gun, solvent, from a line connected to the gun, is pumped through the gun to purge the gun of the resin and catalyst. The solvent not only increases the operating cost of the gun and is harmful to certain components, such as seals, but also produces noxious and volatile fumes when sprayed from the gun. Thus, it is a principal object of the present invention to provide a spray gun for spraying two dissimilar liquids so that they are mixed together after being ejected from the gun.
Another drawback of spray guns designed to receive two dissimilar liquids, such as polyester resin and catalyst, and then eject a mixture of two liquids is that a separate valving mechanism is required for each liquid and an appropriate linkage mechanism is needed to simultaneously operate both valves so that both liquids flow at the same time. Accordingly, it is a further object of the present invention to provide a spray gun employing a single valve mechanism to simultaneously control the flow of two separate liquids thereby simplifying the gun design and reducing its weight and size.
A further related object of the present invention is to provide a spray gun with a singular valve for controlling the flow of two separate liquids with the valve integrally constructed within a gun and requiring only a minimum of machining of the gun.